The present invention relates to electroexplosive devices (EEDs) such as detonators, blasting caps and squibs, and more particularly to a method and apparatus for desensitizing EEDs to electromagnetic radiation and electrostatic charges, thus preventing the premature or inadvertent detonation thereof. Squibs are classified as EED's, even though they may contain a pyrotechnic composition instead of a low explosive. Regardless of whether a low explosive or a pyrotechnic composition is used, the composition is energetic and the function is the same, i.e., start of an explosive train.
A typical EED has a fine-gauge bridgewire imbedded in a chemical compound that explodes when brought to a high temperature, the bridgewire being heated by passing therethrough a relatively small amount of direct current. Because so little energy is required to ignite an EED, it is very sensitive to high frequency radiation which may be readily induced into the input leads and then into the bridgewire. EEDs are also known to be sensitive to transient or spurious signals, stray currents, and static charges.
Various methods have been used to alleviate the problem of misfiring caused by electromagnetic radiation. Prior art systems have included RF traps with inductive and capacitive components, spark gaps, and bypass circuits using diode and capacitor combinations. However, filters having a plurality of discrete components are relatively expensive, and many of the prior RF attenuation systems cannot be readily applied to existing EEDs. In addition, prior attenuators have generally been unsuitable for commercial production because of the costs involved in producing the units.